Cyclosporine (CsA), a selective immunosuppressant and a potent anti-inflammatory agent, has demonstrated great clinical success in inhibiting T-cell mediated immune processes such as allograft rejection, graft-versus-host disease, and autoimmune disease when administered systemically. (See, e.g., A. D. Hess al., Transpl. Proc. 20: 29 (1988).) As to the latter, systemic CsA has been proven efficacious for treating psoriasis autoimmune disorder of the skin. (See, e.g., C. N. Ellis, et al., JAMA 256: 3110 (1986).) However, the induction of tissue site and focal responding immunocytes could result in surprisingly greater efficacy, and could have significant immunologic and clinical ramifications.
As an example of the aforementioned ramifications, within the specialty of dermatology, it would be desirable to treat putative autoimmune conditions and related diseases of the skin, including, for example, eczema, contact hypersensitivity, alopecia areata and psoriasis. Few if any models for testing the disease mechanism and the efficacy of various treatment modalities have been available in this field, however. Moreover, due to the variability of expression of most skin conditions, and the inherent differences between epidermal tissues in various locations on the body, a single treatment methodology or pharmaceutical composition is rarely effective for all disease conditions presented.
A basic understanding of the immune response involved will facilitate the understanding and appreciation of the present invention. T-cell mediated immune events play an important role in eliciting allograft rejection and other inflammatory reactions. The immunological cascade that follows alloengraftment includes: (1) recognition of antigen; (2) lymphocyte activation; (3) development of specific cellular and molecular lines of communication between responding immunocytes via lymphokine release and induced expression of major histocompatibility complex ("MHC") antigens; and (4) mononuclear inflammatory cell infiltration into the target tissue which leads to eventual graft destruction (rejection). Systemic administration of CsA, a novel fungal metabolite, is well known to block this inflammatory cascade and to facilitate permanent allograft acceptance (actively-acquired immunological tolerance) in various experimental animal models, probably by inhibitory effects upon T-helper cells with sparing of cell expression. (See, e.g., A. D. Hess, et al., Transpl. Proc. 29 (1988).) Cyclosporins have novel immunosuppressive properties compared to conventional agents: they are selective in their mechanism of action, demonstrate superior graft survival times, and are potent anti-inflammatory compounds. Cyclosporins are well-recognized for their powerful ability to permanently alter immune responsiveness, in comparison with conventional agents, so that some degree of selective immunologic tolerance (graft acceptance) can be achieved in various models. Therefore, it would be extremely advantageous and desirable to develop topical formulations of cyclosporins for localized tissue site-specific action.
Conventionally, immunosuppressants have been administered at a systemic level in order to inhibit both cell- and humoral-mediated immune responses. However, the induction of localized site-specific immunosuppression could inhibit the mechanisms which lead to graft rejection and similar inflammatory immune processes operative in autoimmune and putative autoimmune disorders. Yet, a tissue site-specific immunosuppressive mechanism has not been conclusively demonstrated by local application of the cyclosporins.
More recently, the fungal metabolites known as cyclosporins, and particularly Cyclosporine A (CsA), have been established as the principal immunosuppressants in solid organ transplantations. The systemic use of cyclosporin prolongs the survival of experimental and clinical allografts, but continuing immunosuppressive therapy is generally necessary.
Yet, the long-term side effects of systemic administration of cyclosporins are of major concern. The related complications of nephrotoxicity and hepatotoxicity (i.e., kidney and liver damage), as well as an increase in infections, are a significant problem and may thus render treatment with cyclosporins inappropriate for certain patients, such as those who have been severely burned, or for those with skin conditions that are not life-threatening, such as psoriasis. One method for achieving indefinite survival of the graft or prolonged anti-inflammatory effects with CsA and for reducing its potentially toxic systemic side effects involves the localization of CsA in the target tissue.
For the purposes of clarity and easier comprehension, the terms "CsA", "Cyclosporine A" and "cyclosporine" may be considered interchangeable with the term "cyclosporin(s)" throughout this disclosure. While CsA is the cyclosporin typically used in most pharmaceutical preparations, the scope of this invention is not limited to this one type of cyclosporin.
Local inhibition of the rejection response with CsA has demonstrated mixed results. Perfusion of kidney allografts with CsA prior to transplantation did produce enhancement of tissue survival; however, prior, minimal systemic azathioprine immunosuppression was required. See, e.g., L. H. Toledo-Pereyra, et al., Transplantation 33: 330 (1982). Likewise, infusion of low-dose CsA into the ligated thoracic duct provided only a mild enhancement of rat kidney allograft survival. Delayed type hypersensitivity has been effectively inhibited in animals and man with topically-applied CsA (see, e.g., R. D. Aldridge, et al., Clin. Exp. Immunol. 59: 23, 1985), as has cornea allograft rejection. The topical application of CsA has also been shown to be effective in treating alopecia areata and contact hypersensitivity in humans, yet it appears to have no effect on psoriasis. Studies using topically-applied CsA demonstrated prolonged survival of rat skin allografts; see, e.g., C. S. Lai, et al., Transplantation 44: 83, 1987; X.F. Zhao, et al., Transplant. Proc. 20: 670 (1988). However, one such study concluded that most of the enhancement observed with local CsA treatment was due to the animals, ingestion of CsA from the treated area. See Zhao, supra. When means were taken to prevent the animals from ingesting CsA from the grafts, the investigators found that CsA blood levels were suboptimal (below 100 ng/ml) and negligible enhancement of skin allograft survival was seen. It has also been postulated that autoimmune disorders of the skin could benefit from transdermal (i.e., localized) treatment with CsA.
Thus, there is a need for topical and local formulations of cyclosporins, and a method for utilizing same, in the prevention of localized tissue site-specific inflammatory immune reactions. An example includes prevention of skin allograft rejection at a local level, but this would serve as a model for other inflammatory disorders such as autoimmune diseases of the skin (i.e., psoriasis, contact hypersensitivity, alopecia areata) and tissue or organ allografts. In particular, a methodology that locally provides allograft acceptance and attenuates T-cell mediated events is highly desirable. The present invention is directed to such a formulation and method of use.
SUMMARY OF THE INVENTION
The present invention exploits the observation that skin allograft survival may be prolonged via topical use of cyclosporins, and more particularly, Cyclosporine A. It is based on the concept that targeting CsA to a specific tissue is a desirable means for increasing efficacy and reducing systemic toxic concerns associated with this immunosuppressant. This localized effect of CsA also indicates potential usefulness in organ transplants, via perfusion and/or topical application. Further, cyclosporins may be effective in the clinical treatment of autoimmune skin disorders and other localized inflammatory reactions. In general, then, this treatment may be appropriate whenever there is a T-cell-mediated or mononuclear cellular inflammatory reaction incited by a fixed-tissue-based antigen and/or unknown mechanisms. In addition, local treatment of rheumatoid arthritis, multiple sclerosis, inflammatory lung disease, and other inflammatory disorders with cyclosporins may prove efficacious.
A critical mechanism for the induction of site-specific immune suppression by CsA appears to be the establishment of a systemic maintenance phase of immune non-responsiveness. To induce this maintenance state, an initial limited systemic dose of CsA appears necessary. Analogously, it is well-recognized that two distinct states of immunosuppression, the induction and maintenance phases, are important for the development of specific immune non-responsiveness. (See, e.g., E. Towpik, et al., Transplantation 40: 714 (1985).) It is not unlikely that CsA dosing requirements for efficacious site-specific suppression of autoimmune inflammatory skin disorders will underscore this observation. Continuous low-dose CsA administered systemically in conjunction with topical application may also prove efficacious.
In accordance with one aspect of the present invention, there is provided a method for utilizing local CsA in a topical formulation in conjunction with a short-term, limited systemic CsA schedule or a longer-term, low-dose systemic CsA schedule for effective abrogation of skin allograft rejection, T-cell mediated immune processes, and inflammatory reactions. This method should also prove effective in the clinical treatment of autoimmune skin disorders including psoriasis and other localized inflammatory reactions or cyclosporin-responsive conditions. One preferred embodiment suggests a systemically applied formulation wherein about 1 mg/kg/day to 15 mg/kg/day of cyclosporin is applied per single dosage.
In one embodiment, CsA is suspended in a topical cream formulation of a particular composition. In another embodiment, CsA is a component of a mineral oil-based topical formulation of a particular composition. In accordance with yet another embodiment of the invention, a topical formulation of cyclosporin is provided wherein CsA is embodied in a jojoba oil-based topical formulation of a particular composition. In accordance with other embodiments, the formulation is embodied in a paste, a gel, a liquid or a spray. Additionally, other embodiments include topical formulations of CsA in conjunction with different immunosuppressants and anti-inflammatory agents. Additional embodiments include formulations containing a preservative, as well.
For example, one preferred type of formulation according to the present invention may generally comprise cyclosporin, a pharmaceutical carrier, a co-solvent, a penetration enhancer, and an emulsifier. In a further embodiment, said components may be present in these approximate quantities: 5-80% pharmaceutical carrier; 5-50% co-solvent; 1-5% penetration enhancer; 0.1-20% emulsifier; and 0.2-25% cyclosporin (or cyclosporin applied to the tissue in such an amount that from about 0.5 mg/cm.sup.2 to 5 mg/cm.sup.2 of cyclosporin is applied per single dose).
Another preferred type of formulation according to the present invention may generally comprise, in approximate amounts by weight, 5-60anhydrous lanolin; 5-60mineral oil; 5-60% olive oil; 5-30% ethyl alcohol; 5-50% deionized water; 5-15% glycerol; 0.2-20% polysorbate 80; 1-5% polyvinylpyrrolidone; 0.2-25% cyclosporine A powder; and 0.1-10% sodium dodecyl sulfate.
Still another preferred type of formulation according to the present invention may generally comprise, in approximate amounts by weight, 5-60% anhydrous lanolin; 5-80% jojoba oil; 5-80% olive oil; 0.2-20% polysorbate 80; and 0.2-25% cyclosporine A powder.
An additional preferred type of formulation according to the present invention may generally comprise, in approximate amounts by weight, 5-60% anhydrous lanolin; 5-80% mineral oil; 5-80% olive oil; 0.2-20% polysorbate 80; and 0.2-25% cyclosporine A powder.
Another preferred type of formulation according to the present invention may generally comprise, in approximate amounts by weight, 5-60% anhydrous lanolin; 5-80% white petrolatum; 5-80% olive oil; 0.2-20% polysorbate 80; and 0.2-25% cyclosporine A powder.
Another preferred type of formulation according to the present invention may generally comprise, in approximate amounts by weight, 60-90% ethyl alcohol; 3-30% glycerol; 0.2-20% polysorbate 80; and 0.2-25% cyclosporine A powder.
According to the present invention, yet another example of a preferred formulation generally comprises, in approximate amounts by weight, 0-50% ethyl alcohol (v/v); 5-30% glycerol (v/v); 10-90% propylene glycol (v/v); and 0.2-25% cyclosporine A powder (w/v).
Another preferred type of formulation according to the present invention may generally comprise, in approximate amounts by weight, 0.2-20% polysorbate 80 (v/v); 2-30% ethyl alcohol (v/v); 5-50% deionized water (v/v); 5-40% glycerol (v/v); 10-80% propylene glycol (v/v); and 0.2-25% cyclosporine A powder (g/100 ml; w/v).
Another preferred type of formulation according to the present invention may generally comprise, in approximate amounts by weight, 0-20% ethanol (v/v); 0.2-25% cyclosporin (w/v); 19-80% white petrolatum (v/v); 0-10% heavy mineral oil (v/v); and 0.05-5% steroid powder (w/v). A further embodiment may utilize hydrocortisone as the steroid powder of choice.
Yet another preferred type of formulation according to the present invention may generally comprise cyclosporin and a pharmaceutically acceptable pharmaceutical carrier. Such a formulation may further comprise an esterification product of natural triglycerides and polyethylene glycol; a vegetable oil; and ethanol.
Another preferred type of formulation according to the present invention may generally comprise a formulation wherein the weight ratio of ester to cyclosporin is about 10: 0.2 to 10 parts by weight; vegetable oil is about 35 to 60% of the total composition by weight; and ethanol is about 1 to 20% of the total composition by weight. Further, such a formulation may generally include cyclosporin, wherein the cyclosporin is cyclosporin A powder in a concentration by weight of about 0.5% to about 25%.
In accordance with another aspect of the present invention, a dual skin graft model is provided, which may be used, for example, to test treatment protocols, such as the tandem treatment method suggested herein, or the topical administration of various cyclosporin-containing formulations.
Further, the present invention proposes that the use of pharmaceutically acceptable co-solvents and potential penetration promoters in cyclosporin-containing topical treatment formulations may result in decreased or lost efficacy locally, but increased efficacy systemically. Therefore, a gradient effect may be created by such formulations in the locally-treated tissues which extends into the systemic circulation. However, by lowering cyclosporin doses with such formulations, the potentially desired local result can be effected. In contradistinction, topical cyclosporin formulations without said co-solvents and obvious penetration promoters generally appear to facilitate deposition of the active agent locally in the treated tissues. These latter formulations are more effective at producing only localized effects without systemic involvement at equivalent cyclosporin concentrations.
In addition, it is suggested that various combinations of cyclosporins, steroids and other anti-inflammatory agents (non-steroidal agents, for example) be used in the local treatment of autoimmune and other inflammatory conditions to provide combined, additive, and/or synergistic efficacy.
In another embodiment of the present invention, alternative delivery systems, such as microencapsulation of cyclosporin-containing formulations within lipid membranous vesicles such as liposomes, are suggested.
Other embodiments of the present invention include the effective administration of CsA for systemic purposes via transdermal application. It is thought that this novel route of administration of CsA may provide new mechanisms of systemic action of CsA due to different metabolism when cyclosporin passes through the epidermis/dermis. These results also support the use of topical CsA formulations as an effective means for systemic delivery in patients needing immunosuppression but who may present compromised gastrointestinal absorption.
In addition, it is suggested, in another embodiment, that CsA may be administered locally to various tissues other than the skin; e.g., to the oral mucosa, the esophagus, the nasal septum, the bronchial tubes, and lung tissue, to name a few.
Moreover, CsA has been shown to have mild antifungal properties and topical application may be effective for fungal infections. Such application is suggested in another embodiment of the present invention.
Finally, the present invention proposes a method for utilizing any one of several topical CsA formulations in conjunction with systemically-applied CsA, or independently of same.
One advantage of the present invention over the prior art includes the fact that topical application of cyclosporin is effective in abrogating skin allograft rejection, inflammatory reactions and autoimmune skin disorders, without interfering with other cellular processes, apparently. As noted previously, other topically-applied formulations, such as those containing steroids, are less efficacious immunosuppressants, are less selective in their actions, and are less effective at inducing permanent immunologic tolerance than are cyclosporins. Further, in the case of steroid creams and ointments, a detrimental effect on wound healing and non-specific immunity against infection may result from their use.
A further advantage of the present invention is the fact that selectively delivering cyclosporin to a specific tissue targets the compound to responsive inflammatory cells and is a desirable means of increasing efficacy and reducing systemic toxic concerns associated with this immunosuppressant, in that the localized effect of cyclosporin indicates that it is potentially useful in organ transplants via topical application and/or via perfusion. Topical application of cyclosporin promotes allograft survival by delivering the compound to the target tissue, which facilitates the site-specific activity and efficacy of this immunosuppressant, while reducing potentially toxic systemic levels of cyclosporin.
Another advantage of the present invention is the fact that the dual skin allograft model provides an excellent research and clinical study protocol. For example, use of two allografts, one receiving treatment and the other left untreated, allows in vivo assessment of the systemic T-cell mediated response against the particular allograft in question. Since the treated allograft will potentially elicit systemic alloactivation, assessment of the test substance's ability to locally suppress these systemic alloaggressive cells will be possible. In addition, local effects of a test substance may be studied via the proposed dual skin allograft model.
Further advantages include the efficacy of the invention in treating a disease such as alopecia, where relatively normal skin is receiving treatment. In such instances, the required formulation is likely to be different from that which would effectively treat a more severe skin disorder such as psoriasis complicated by open lesions. In addition, dose and timing requirements will require study of the patient by the practitioner, and may necessitate variations for both systemic and topical phases of treatment.
Likewise, some conditions may require topical application alone, without prior systemic CsA treatment. Moreover, different formulations may easily be devised according to the protocols and methods set forth herein, to produce creams or ointments which may prove efficacious and advantageous.